Re: [PATCH v13 7/8] allower the user to disable pv event support

Paolo Bonzini
2013-03-04T09:53:25Z

Il 28/02/2013 13:13, Hu Tao ha scritto:
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
> hw/pc_piix.c | 9 ++++++++-
> qemu-options.hx | 3 ++-
> vl.c | 4 ++++
> 3 files changed, 14 insertions(+), 2 deletions(-)

We cannot add -machine suboptions for everything we add to a random
machine type. I think it's better to do one of the following:

1) not add it to the machine by default. Let libvirt add it with -device.

2) add a property to the piix3 ISA bridges (in hw/piix_pci.c) to
enable/disable it. It can be set with -global PIIX3.pv_event=on/off.

In the second case, if you set it to on by default, you will also need
to add the property in hw/pc.h, to disable the device in older machine
types for backwards-compatibility.

Paolo

> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 24a9bf3..82a421a 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -44,6 +44,7 @@
> #include "exec/memory.h"
> #include "exec/address-spaces.h"
> #include "cpu.h"
> +#include "qemu/config-file.h"
> #ifdef CONFIG_XEN
> # include <xen/hvm/hvm_info_table.h>
> #endif
> @@ -86,6 +87,8 @@ static void pc_init1(MemoryRegion *system_memory,
> MemoryRegion *pci_memory;
> MemoryRegion *rom_memory;
> void *fw_cfg = NULL;
> + QemuOptsList *list = qemu_find_opts("machine");
> + bool enable_pv_event = false;
>
> pc_cpus_init(cpu_model);
> pc_acpi_init("acpi-dsdt.aml");
> @@ -218,7 +221,11 @@ static void pc_init1(MemoryRegion *system_memory,
> pc_pci_device_init(pci_bus);
> }
>
> - if (kvm_enabled()) {
> + if (list && !QTAILQ_EMPTY(&list->head)) {
> + enable_pv_event = qemu_opt_get_bool(QTAILQ_FIRST(&list->head),
> + "enable_pv_event", false);
> + }
> + if (kvm_enabled() && enable_pv_event) {
> kvm_pv_event_init(isa_bus);
> }
> }
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 797d992..1ad4041 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -35,7 +35,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
> " kernel_irqchip=on|off controls accelerated irqchip support\n"
> " kvm_shadow_mem=size of KVM shadow MMU\n"
> " dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
> - " mem-merge=on|off controls memory merge support (default: on)\n",
> + " mem-merge=on|off controls memory merge support (default: on)\n"
> + " enable_pv_event=on|off controls pv event support (default: off)\n",
> QEMU_ARCH_ALL)
> STEXI
> @item -machine [type=]@var{name}[,prop=@var{value}[,...]]
> diff --git a/vl.c b/vl.c
> index 51d4922..5b3a279 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -427,6 +427,10 @@ static QemuOptsList qemu_machine_opts = {
> .name = "usb",
> .type = QEMU_OPT_BOOL,
> .help = "Set on/off to enable/disable usb",
> + }, {
> + .name = "enable_pv_event",
> + .type = QEMU_OPT_BOOL,
> + .help = "handle pv event"
> },
> { /* End of list */ }
> },
>